First: I''m new to Ruby
Simple model:
class Product < ActiveRecord::Base
def save
STDERR << "save: " << @name << "\n"
STDERR << "save: " << self.name <<
"\n"
end
end
I thought that both lines should give the same result...
--
Posted via http://www.ruby-forum.com/.
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I''m pretty new to Ruby myself, I''ve kinda learned as required so I''m patchy. From what I''ve seen however, I think ''self'' is relative to the current scope, i.e instance or class. Where as @ is always in instance scope. Ian. On 28/08/06, Joep Mathijssen <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote:> > > First: I''m new to Ruby > > Simple model: > > class Product < ActiveRecord::Base > > def save > STDERR << "save: " << @name << "\n" > STDERR << "save: " << self.name << "\n" > end > end > > I thought that both lines should give the same result... > > -- > Posted via http://www.ruby-forum.com/. > > > >--~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk -~----------~----~----~----~------~----~------~--~---
self is the object itself. self.name is saying that there''s a public method on self to be called (attr_reader :name) @name says ''get the instance variable @name for this class instance'' Use ''self'' pretty much the same way you''d use ''this'' in Java or C++, though not in the cases that you can use @ (passing yourself to another method is the most used example). Jason On 8/28/06, Ian Leitch <port001-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:> > I''m pretty new to Ruby myself, I''ve kinda learned as required so I''m > patchy. > > From what I''ve seen however, I think ''self'' is relative to the current > scope, i.e instance or class. Where as @ is always in instance scope. > > Ian. > > > On 28/08/06, Joep Mathijssen <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote: > > > > > > First: I''m new to Ruby > > > > Simple model: > > > > class Product < ActiveRecord::Base > > > > def save > > STDERR << "save: " << @name << "\n" > > STDERR << "save: " << self.name << "\n" > > end > > end > > > > I thought that both lines should give the same result... > > > > -- > > Posted via http://www.ruby-forum.com/ . > > > > > > > >--~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk -~----------~----~----~----~------~----~------~--~---
dblack-TKXtfPMJ4Ozk1uMJSBkQmQ@public.gmane.org
2006-Aug-28 21:58 UTC
Re: Difference instance variable @ or self.
Hi -- On Mon, 28 Aug 2006, Jason Roelofs wrote:> > On 8/28/06, Ian Leitch <port001-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote: >> >> On 28/08/06, Joep Mathijssen <rails-mailing-list-ARtvInVfO7ksV2N9l4h3zg@public.gmane.org> wrote: >>> >>> First: I''m new to Ruby >>> >>> Simple model: >>> >>> class Product < ActiveRecord::Base >>> >>> def save >>> STDERR << "save: " << @name << "\n" >>> STDERR << "save: " << self.name << "\n" >>> end >>> end >>> >>> I thought that both lines should give the same result... >> >> I''m pretty new to Ruby myself, I''ve kinda learned as required so I''m >> patchy. >> >> From what I''ve seen however, I think ''self'' is relative to the current >> scope, i.e instance or class. Where as @ is always in instance scope.self is the "default object". There''s always one and only one self at any point in a Ruby program. Since classes are objects, self can be a class: class SelfTest p self end # => output: SelfTest Instance variables are a way for individual objects (including Class objects) to store information and maintain state. Every object has its own instance variables. There''s a tight connection between instance variables and self: whenever you see @var, @name, etc., you''re seeing an instance variable that belongs to self.> self is the object itself. > > self.name is saying that there''s a public method on self to be called > (attr_reader :name)All it really says is that you''re sending the message ''name'' to the object self. Usually you do that in cases where there''s a corresponding method -- but not always. attr_reader isn''t connected to this; there are many methods you can call on objects that aren''t created with attr-reader.> @name says ''get the instance variable @name for this class instance''More precisely: @name is the instance variable @name belonging to self (whatever self is at that given moment in runtime). David -- David A. Black | dblack-TKXtfPMJ4Ozk1uMJSBkQmQ@public.gmane.org Author of "Ruby for Rails" [1] | Ruby/Rails training & consultancy [3] DABlog (DAB''s Weblog) [2] | Co-director, Ruby Central, Inc. [4] [1] http://www.manning.com/black | [3] http://www.rubypowerandlight.com [2] http://dablog.rubypal.com | [4] http://www.rubycentral.org --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk -~----------~----~----~----~------~----~------~--~---